1. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 1 Process Improvement 1

2. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 2 l To explain the principles of software process improvement l To explain how software process factors influence software quality and productivity l To explain how to develop simple models of software processes l To explain the notion of process capability and the CMMI process improvement model Objectives

3. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 3 l Understanding existing processes and introducing process changes to improve product quality, reduce costs or accelerate schedules. l Most process improvement work so far has focused on defect reduction. This reflects the increasing attention paid by industry to quality. l However, other process attributes can also be the focus of improvement Process improvement

4. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 4 Process attributes

5. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 5 The process improvement cycle

6. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 6 l Process measurement Attributes of the current process are measured. These are a baseline for assessing improvements. l Process analysis The current process is assessed and bottlenecks and weaknesses are identified. l Process change Changes to the process that have been identified during the analysis are introduced. Process improvement stages

7. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 7 l Process quality and product quality are closely related and process improvement benefits arise because the quality of the product depends on its development process. l A good process is usually required to produce a good product. l For manufactured goods, process is the principal quality determinant. l For design-based activity, other factors are also involved especially the capabilities of the designers. Process and product quality

8. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 8 Principal product quality factors

9. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 9 Quality factors l For large projects with ‘average’ capabilities, the development process determines product quality. l For small projects, the capabilities of the developers is the main determinant. l The development technology is particularly significant for small projects. l In all cases, if an unrealistic schedule is imposed then product quality will suffer.

10. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 10 l Informal No detailed process model. Development team chose their own way of working. l Managed Defined process model which drives the development process. l Methodical Processes supported by some development method such as the RUP. l Supported Processes supported by automated CASE tools. Process classification

11. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 11 Process applicability

12. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 12 l Process used should depend on type of product which is being developed For large systems, management is usually the principal problem so you need a strictly managed process; For smaller systems, more informality is possible. l There is no uniformly applicable process which should be standardised within an organisation High costs may be incurred if you force an inappropriate process on a development team; Inappropriate methods can also increase costs and lead to reduced quality. Process choice

13. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 13 Process tool support

14. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 14 l Wherever possible, quantitative process data should be collected However, where organisations do not have clearly defined process standards this is very difficult as you don’t know what to measure. A process may have to be defined before any measurement is possible. l Process measurements should be used to assess process improvements But this does not mean that measurements should drive the improvements. The improvement driver should be the organizational objectives. Process measurement

15. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 15 l Time taken for process activities to be completed E.g. Calendar time or effort to complete an activity or process. l Resources required for processes or activities E.g. Total effort in person-days. l Number of occurrences of a particular event E.g. Number of defects discovered. Classes of process measurement

16. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 16 l Goals What is the organisation trying to achieve? The objective of process improvement is to satisfy these goals. l Questions Questions about areas of uncertainty related to the goals. You need process knowledge to derive these. l Metrics Measurements to be collected to answer the questions. Goal-Question-Metric Paradigm

17. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 17 Process analysis and modelling l Process analysis The study of existing processes to understand the relationships between parts of the process and to compare them with other processes. l Process modelling The documentation of a process which records the tasks, the roles and the entities used; Process models may be presented from different perspectives.

18. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 18 l Study an existing process to understand its activities. l Produce an abstract model of the process. You should normally represent this graphically. Several different views (e.g. activities, deliverables, etc.) may be required. l Analyse the model to discover process problems. This involves discussing process activities with stakeholders and discovering problems and possible process changes. Process analysis and modelling

19. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 19 l Published process models and process standards It is always best to start process analysis with an existing model. People then may extend and change this. l Questionnaires and interviews Must be carefully designed. Participants may tell you what they think you want to hear. l Ethnographic analysis Involves assimilating process knowledge by observation. Best for in-depth analysis of process fragments rather than for whole-process understanding. Process analysis techniques

20. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 20 Process model elements 1

21. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 21 Process model elements 2

22. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 22 The module testing activity

23. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 23 Activities in module testing

24. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 24 Process exceptions l Software processes are complex and process models cannot effectively represent how to handle exceptions: Several key people becoming ill just before a critical review; A breach of security that means all external communications are out of action for several days; Organisational reorganisation; A need to respond to an unanticipated request for new proposals. l Under these circumstances, the model is suspended and managers use their initiative to deal with the exception.

25. ©Ian Sommerville 2004Software Engineering, 7th edition. Chapter 28 Slide 25 l Process improvement involves process analysis, standardisation, measurement and change. l Processes can be classified as informal, managed, methodical and improving. This classification can be used to identify process tool support. l Process improvement involves process measurement, analysis and change. l Process measurement should be used to answer specific questions based on organisational improvement goals. l Process models include descriptions of tasks, activities, roles, exceptions, communications, deliverables and other processes. Key points